Gold is a bright yellow, soft metal that occurs naturally in rocks and alluvial deposits. It is mined through both placer mining, where gold is extracted from loose sediment, and hard rock mining, where gold is encased in rock. Hard rock mining techniques include both open-pit and underground mining. Once extracted, gold is further refined through processes like electrolysis or chlorination to achieve higher purity for industrial and commercial applications such as jewelry, investments, and dentistry.

1. GOLD
-A SHINING MINERAL

2. WHAT IS GOLD ?
• Gold is a chemical element with symbol Au and atomic
number 79. In its purest form, it is a bright, slightly reddish
yellow, dense, soft, malleable and ductile metal Chemically,
gold is a transition metal and a group 11 element. It is one of
the least reactive chemical elements, and is solid
under standard conditions. The metal therefore occurs often
in free elemental form, as nuggets or grains, in rocks,
in veins and in alluvial deposits. It occurs in a solid
solution series with the native element silver and also
naturally alloyed with copper and palladium. Less
commonly, it occurs in minerals as gold compounds, often
with tellurium (gold tellurides).

3. EXTRACTION OF GOLD
Gold extraction is most economical in large, easily
mined deposits. Ore grades as little as 0.5 mg/kg (0.5
parts per million, ppm) can be economical. Typical ore
grades in open-pit mines are 1–5 mg/kg (1–5 ppm); ore
grades in underground or hard rock mines are usually
at least 3 mg/kg (3 ppm). Because ore grades of
30 mg/kg (30 ppm) are usually needed before gold is
visible to the naked eye, in most gold mines the gold is
invisible.
The average gold mining and extraction costs were
about US$317/oz in 2007, but these can vary widely
depending on mining type and ore quality; global mine
production amounted to 2,471.1 tonnes.

4. GOLD MINING
Gold mining is the process of mining of gold or
gold ores from the ground. There are several
techniques and processes by which gold may be
extracted from the earth.
• Placer mining
Placer mining is the technique by which gold that has
accumulated in a placer deposit is extracted. Placer deposits are
composed of relatively loose material that makes tunneling
difficult, and so most means of extracting it involve the use of
water or dredging.

5. GOLD MINING
• Panning
Gold panning is mostly a manual technique of separating gold
from other materials. Wide, shallow pans are filled with sand and
gravel that may contain gold. The pan is submerged in water and
shaken, sorting the gold from the gravel and other material. As
gold is much denser than rock, it quickly settles to the bottom of
the pan. The panning material is usually removed from stream
beds, often at the inside turn in the stream, or from the bedrock
shelf of the stream, where the density of gold allows it to
concentrate, a type called placer deposits.

6. GOLD MINING
• Hard rock mining
Hard rock gold mining extracts gold encased in rock, rather than
fragments in loose sediment, and produces most of the world's gold.
Sometimes open-pit mining is used, such as at the Fort Knox Mine in
central Alaska. Barrick Gold Corporation has one of the largest open-
pit gold mines in North America located on its Goldstrik mine property
in northeastern Nevada. Other gold mines use underground mining,
where the ore is extracted through tunnels or shafts. South Africa has
the world's deepest hard rock gold mine up to 3,900 metres
underground. At such depths, the heat is unbearable for humans, and
air conditioning is required for the safety of the workers. The first such
mine to receive air conditioning was Robinson Deep, at that time the
deepest mine in the world for any mineral.

7. REFINING OF GOLD
After initial production, gold is often subsequently
refined industrially by the Wohlwill process which is
based on electrolysis or by the Miller process, that is
chlorination in the melt. The Wohlwill process
results in higher purity, but is more complex and is
only applied in small-scale installations. Other
methods of assaying and purifying smaller amounts
of gold include parting and inquartation as well
as cupellation, or refining methods based on the
dissolution of gold in aqua regia.

8. APPLICATIONS OF GOLD
• Jewellery
• Investments
• Commercial Chemistry
• Industrial Uses
• Foods
• Monetary Exchange
• Filling of Teeth